I'm not sure why you'd say it's not the best bag in the world. Kelty's a good brand, with a good, solid reputation. If it keeps you warm, stores well in your pack, and is lighter than what you've got, it sounds like the best bag for your needs.

"Best" to me means that it gives you the best balance of comfort, weight, function, and cost. Where that best balance is varies widely from person to person, and nobody is right or wrong.

It may not be lightest, or the most expensive, or whatever particular quality you want to name. But if it works, and works for you, it's the best piece of gear.